Decoding circuit

ABSTRACT

There is provided a decoding circuit including; a first decoding unit that decodes a first signal from a multiplexed signal in which the first signal and a second signal are multiplexed in an LDM (Layered Division Multiplexing) system; and a second decoding unit that decodes the second signal from the multiplexed signal using the decoding result of the decoded first signal, wherein the second signal is selectively decoded based on noise information related to a reception state of the multiplexed signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase of International PatentApplication No. PCT/JP2019/028914 filed on Jul. 23, 2019, which claimspriority benefit of Japanese Patent Application No. JP 2018-142608 filedin the Japan Patent Office on Jul. 30, 2018. Each of theabove-referenced applications is hereby incorporated herein by referencein its entirety.

TECHNICAL FIELD

The present disclosure relates to a decoding circuit.

BACKGROUND ART

As a method to multiplex broadcasting signals, a technique to multiplexsignals in a power direction, called the LDM (Layered DivisionMultiplexing) system, has been developed. For example, the technique isdisclosed in PTL 1 and 2.

CITATION LIST Patent Literature

[PTL1]

Japanese Translation of PCT Application No. 2017-527167

[PTL2]

Japanese Translation of PCT Application No. 2018-504005

SUMMARY Technical Problem

In a case of multiplexing two types of signals in the LDM system, thesetwo types of signals are called a core layer signal and an enhancedlayer signal, for example. In a case of decoding a multiplex signalmultiplexed in the LDM system, the core layer signal is decoded first,then the enhanced layer signal is decoded using the decoding result thecore layer signal.

In order to be successful in decoding the enhanced layer signal, thedecoding of the core layer signal must be successful first. However, insome cases, even if processing fails in the middle of decoding the corelayer signal, decoding of the enhanced layer signal may be successful.

This disclosure proposes a decoding circuit that can decode themultiplexed signal more efficiently in the LDM system.

Solution to Problem

A decoding circuit that is provided according to the present disclosureincludes: a first decoding unit that decodes a first signal from amultiplexed signal in which the first signal and a second signal aremultiplexed in an LDM system; and a second decoding unit that decodesthe second signal from the multiplexed signal, and the second signal isselectively decoded based on noise information related to a receptionstate of the multiplexed signal.

Another decoding circuit that is provided according to the presentdisclosure includes: a first decoding unit that decodes a first signalfrom a multiplexed signal in which the first signal and a second signalare multiplexed in an LDM system; and a second decoding unit thatdecodes the second signal from the multiplexed signal, and the secondsignal is selectively decoded based on the decoding result of the firstsignal.

Advantageous Effects of Invention

According to present disclosure, multiplexed signal can be moreefficiently decoded in the LDM system.

It should be noted that the above effect is not limited, and any effectindicated in the present description or a different effect that may begrasped based on the present description may be implemented along withor instead of the above-mentioned effect.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram for explaining an overview of multiplexing in theLDM system.

FIG. 2 is a diagram for explaining an example of a signal processingsystem 1000 according to a decoding processing.

FIG. 3 is a block diagram depicting a configuration example of ademodulating circuit 200 according to Embodiment 1.

FIG. 4 is a block diagram depicting a configuration example of adecoding unit 240 according to Embodiment 1.

FIG. 5 is a diagram for explaining SN (Signal Noise) estimationaccording to Embodiment 1.

FIG. 6 is a flow chart depicting an example of an operation flow of thedecoding unit 240 to decode a multiplexed signal according to Embodiment1.

FIG. 7 is a diagram for explaining a modification of the decoding unit240.

FIG. 8 is a block diagram depicting a functional configuration exampleof a decoding unit 240 according to Embodiment 2.

FIG. 9 is a flow chart depicting an example of an operation flow of thedecoding unit 240 to decode a multiplexed signal according to Embodiment2.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will now be described withreference to the accompanying drawings. In the present description anddrawings, composing elements having substantially a same functionalconfiguration are denoted with a same reference sign, and redundantexplanation thereof is omitted.

Description will be performed according to the following sequence.

-   -   1. Overview    -   2. Embodiment 1    -   2-1. Configuration of signal processing system 1000 according to        Embodiment 1    -   2-2. Configuration example of demodulating circuit 200 according        to Embodiment 1    -   2-3. Configuration example of decoding unit 240 according to        Embodiment 1    -   2-4. Example of operation flow of decoding unit 240 according to        Embodiment 1    -   3. Embodiment 2    -   3-1. Configuration example of decoding unit 240 according to        Embodiment 2    -   3-2. Example of operation flow of decoding unit 240 according to        Embodiment 2    -   4. Embodiment 3    -   5. Conclusion

1. OVERVIEW

An overview of an embodiment of the present disclosure will be describedfirst. In recent years, ATSC (Advanced Television Systems Committee) 3.0was developed as a standard of digital television broadcasting. In theATSC 3.0 standard, the LDM system is used as a method of multiplexingsignals. The LDM system here refers to a multiplexing system in which aplurality of signals, each of which has a different power, arecollectively transmitted as one signal.

In the ATSC 3.0 standard, a first signal and a second signal aremultiplexed in the LDM system. The first signal and the second signalare also called a core layer signal and an enhanced layer signalrespectively. The core layer signal is used for such an application asmobile communication, for example. The enhanced layer signal is used forsuch an application as stationaries and televisions. In the case ofdecoding a broadcasting signal in which the two types of signals aremultiplexed in the LDM system (hereafter called “multiplexed signal”), areceiver must decode the core layer signal first, then decode theenhanced layer signal.

FIG. 1 is a diagram for explaining an overview of multiplexing in theLDM system. In FIG. 1 , various constellations related to the LDM systemare illustrated. Here signal points of a core layer signal are indicatedas a constellation L1. Further, signal points of an enhanced layersignal are indicated as a constellation L2. In the case of transmission,the core layer signal and the enhanced signal are multiplexed, and amultiplexed signal is generated. Signal points of the generatedmultiplexed signal are indicated as a constellation L3. Here aconstellation refers to a diagram generated by plotting the signalpoints of data, when a signal is digitally modulated, on an IQ plane.Further, the IQ plane refers to a two-dimensional complex plane of whichabscissa is an in-phase axis (I axis), and ordinate is a quadrature axis(Q axis).

The receiver receives the multiplexed signal. Then the receiver decodesthe core layer signal first. The receiver extracts data of the corelayer signal by this decoding. In FIG. 1 , the signal points of thesignal in this decoding result are indicated as a constellation L4. Whenthe core layer signal is decoded, the enhanced layer signal is treatedas noise.

Then the receiver acquires the enhanced layer signal by subtracting theresult of decoding the core layer signal from the signal acquired afterdecoding the core layer signal. In FIG. 1 , the signal points of theacquired enhanced layer signal are indicated as a constellation L5. Thereceiver extracts the data of the enhanced layer signal by decoding theacquired enhanced layer signal.

As described above, in the case of the multiplexed signal, which ismultiplexed in the LDM system, the decoding result of the core layersignal is used for decoding the enhanced layer signal. Therefore, inorder to succeed in decoding the enhanced layer signal, decoding of thecore layer signal must be successful. This means that executing decodingof the enhanced layer signal when decoding of the core layer signalfailed consumes power needlessly. A possible countermeasure is that inthe case where decoding of the core layer signal failed, decodingprocessing of the enhanced layer signal is not executed in order toreduce power consumption.

To decode the core layer signal and the enhanced layer signal, the LDPC(Low Density Parity Check) decoding is performed, then the BCH decodingis performed, in the case of the ATSC 3.0 standard, for example.

As described above, in order to succeed in decoding the enhanced layersignal, decoding of the core layer signal must be successful. However,in some cases where the enhanced layer signal is decoded using theresult of the LDPC decoding of the core layer signal, decoding of theenhanced layer signal may be successful even if this LDPC decodingfailed, under such a predetermined condition as burst noise. In such acase, processing efficiency drops if decoding of the enhanced layersignal is stopped, in order to reduce power consumption for example,when the LDPC decoding of the core layer signal failed.

The technical idea according to an embodiment of the present disclosurewas conceived with the foregoing in view, so that a first signal isdecoded from a multiplexed signal in which the first signal and a secondsignal are multiplexed in the LDM system, and the second signal isselectively decoded from the multiplexed signal based on the noiseinformation. Because of this function, the multiplexed signal can bedecoded more efficiently in the LDM system.

2. EMBODIMENT 1 2-1. Configuration of Signal Processing System 1000According to Embodiment 1

FIG. 2 is a diagram for explaining an example of a signal processingsystem 1000 according to a decoding processing. As indicated in FIG. 2 ,the signal processing system 1000 includes a receiving circuit 100, ademodulating circuit 200 and a processing circuit 300. “The receivingcircuit 100 and the demodulating circuit 200” and “the demodulatingcircuit 200 and the processing circuit 300” are electrically connectedvia one or plurality of wires respectively, and various signals (analogsignals or digital signals) are transmitted between circuits.

(Receiving Circuit 100)

The receiving circuit 100 is a circuit (or circuit group) that has afunction to receive broadcasting signals.

For example, the receiving circuit 100 includes an antenna (notillustrated), a first filter (not illustrated), an amplifier (notillustrated), a mixer (not illustrated) and a second filter (notillustrated).

The antenna (not illustrated) is constituted of an antenna having anarbitrary configuration, such as a dipole antenna, a monopole antenna, achip antenna or a pattern antenna, for example, and receives radio wavesthat carry the broadcasting signal. The first filter (not illustrated)is constituted of an arbitrary filter, such as a low-pass filter and aband-pass filter, for example, and removes unnecessary frequencycomponents from a signal received by the antenna (not illustrated). Theamplifier (not illustrated) is constituted of an arbitrary amplifier,such as an LNA (Low-Noise Amplifier), and amplifies a signal transmittedfrom the first filter (not illustrated). A signal transmitted from theamplifier (not illustrated) and a signal having a predeterminedfrequency generated by an oscillator (not illustrated) or the like areinputted to the mixer (not illustrated), and the mixer (not illustrated)converts the signal transmitted from the amplifier (not illustrated)into an IF (intermediate Frequency) signal. The second filter (notillustrated) is constituted of an arbitrary filter, such as a low-passfilter and a band-pass filter, and removes unnecessary frequencycomponents from the IF signal. The signal outputted from the secondfilter (not illustrated) corresponds to the broadcasting signal(modulation signal modulated by a predetermined system) received in thereceiving circuit 100.

The configuration of the receiving circuit 100 is not limited to theabove-mentioned example. The receiving circuit 100 may have an arbitraryconfiguration that can receive broadcasting signals transmitted viaradio waves, for example.

(Demodulating Circuit 200)

The demodulating circuit 200 is a circuit (or circuit group) that has afunction to demodulate a multiplexed signal received by the receivingcircuit 100. The demodulating circuit 200 demodulates a multiplexedsignal that has been multiplexed in the LDM system. The modulatingcircuit 200 can also determine noise information related to a receptionstate of the multiplexed signal. The noise information is used fordecoding processing of the multiplexed signal. The noise informationwill be described later.

The demodulating circuit 200 includes a demodulating unit 220 and adecoding unit 240 which will be described later.

An example of the demodulating circuit 200 is “an IC (integratedCircuit) chip which includes one processor or two or more processors,and in which various circuits to implement the functions of thedemodulating circuit 200 are integrated”. Needless to say, thedemodulating circuit 200 need not be implemented in the form of an ICchip.

The demodulating circuit 200 may include a part of or all of theconfiguration of the receiving circuit 100. In other words, thedemodulating circuit 200 indicated in FIG. 2 may further include a partof or all of the functions of the receiving circuit 100 indicated inFIG. 2 . In the case where the demodulating circuit 200 further includesa part of or all of the functions of the receiving circuit 100, the partof or all of the configuration of the receiving circuit 100 included inthe demodulating circuit 200 play a role of the receiving unit in thedemodulating circuit 200.

(Processing Circuit 300)

The processing circuit 300 is a circuit (or circuit group) thatprocesses a broadcasting signal demodulated by the demodulating circuit200, that is, the core layer data and the enhanced layer data (hereaftermay be referred to as “E layer data”) extracted by the demodulatingcircuit 200.

The signal processing system 1000 demodulates a received broadcastingsignal, and processes the demodulated broadcasting signal using theconfiguration indicated in FIG. 2 , for example.

The configuration of the signal processing system according to thepresent embodiment is not limited to the example indicated in FIG. 2 .

For example, in the case of being connected electrically to an externalreceiving circuit which has similar functions and configuration to thereceiving circuit 100, the signal processing system 1000 according tothe present embodiment may not include the receiving circuit 100indicated in FIG. 2 .

Further, the demodulating circuit 200 indicated in FIG. 2 may include apart of or all of the configuration of the receiving circuit 100. Anexample of the configuration of the demodulating circuit 200 whichincludes a part of the configuration of the receiving circuit 100 is “aconfiguration in which the demodulating circuit 200 is connected to anexternal antenna (an example of a part of the configuration of thereceiving circuit 100)”. The demodulating circuit 200 connected to theexternal antenna processes broadcasting signals received by thisantenna.

Furthermore, the signal processing system according to the presentembodiment may include a part of or all of a processor (notillustrated), a ROM (Read Only Memory, not illustrated), a RAM (RandomAccess Memory, not illustrated), a recording medium (not illustrated), adisplay device (not illustrated), a voice output device (notillustrate), an operation device (not illustrated) and a communicationdevice (not illustrated). The signal processing system according to thepresent embodiment may have a configuration in accordance with anapplication example of the signal processing system of the presentembodiment, which will be described later.

The processor (not illustrated) is constituted of such an arithmeticcircuit as an MPU (microprocessing unit), and has a function to controlthe signal processing according to the present embodiment in general,for example. In the signal processing system 1000 indicated in FIG. 2 ,the processing circuit 300 may play a role of the processor (notillustrated).

The ROM (not illustrated) stores data for control, such as programs usedby the processor (not illustrated) and operation parameters. The RAM(not illustrated) temporarily stores programs executed by the processor(not illustrated), for example.

The recording medium (not illustrated) is a storage unit included in thesignal processing system according to the present embodiment, and storesvarious data, such as data related to the processing method used in thedemodulating circuit 200, for example. An example of the recordingmedium (not illustrated) is a non-volatile memory, such as a flashmemory. It should be noted that the signal processing system accordingto the present embodiment may not include the recording medium (notillustrated), but various data, such as data related to the processingmethod according to the present embodiment, may be stored in an externalrecording medium of the signal processing system according to thepresent embodiment.

The display device (not illustrated) displays various images, such as animage related to a UI (User Interface), on the display screen, forexample. Examples of the display device (not illustrated) are a liquidcrystal display and an organic EL display. The display device may be adevice which can perform display and operation, such as a touch panel,for example

The voice output device (not illustrated) outputs various voices, suchas voices (including music), in accordance with the broadcastingsignals, for example. An example of the voice output device (notillustrated) is a speaker.

The operation device (not illustrated) is a device which a user of thesignal processing system according to the present embodiment canoperate. Examples of the operation device (not illustrated) are buttons,directional keys, rotating type selector (jog dial, for example) or acombination of these devices.

The communication device (not illustrated) is a communication unitincluded in the signal processing system according to the presentembodiment, and plays a role of communicating with an external devicewirelessly or via cable. Examples of the communication device (notillustrated) are: a communication antenna and an RF (Radio Frequency)circuit (radio communication); an IEEE 802.15.1 port and atransmitting/receiving circuit (radio communication); an IEEE 802.11port and a transmitting/receiving circuit (radio communication); and aLAN (Local Area Network) terminal and a transmitting/receiving circuit(cable communication).

In the following, a case where the multiplexed signal is a signal inwhich a first signal and a second signal are multiplexed will bedescribed as an example. Here the first signal is the core layer signal,and the second signal is the enhanced layer signal. The first signal andthe second signal are multiplexed based on the ATSC 3.0 standard, forexample. Needless to say, the signals that the signal processing systemaccording to the present embodiment can process are not limited to thesignals conforming to the ATSC 3.0 standard.

2-2. Configuration Example of Demodulating Circuit 200 According toEmbodiment 1

A configuration example of the demodulating circuit 200 according to anembodiment of the present disclosure will be described next. FIG. 3 is ablock diagram depicting a configuration example of the demodulatingcircuit 200 according to the present embodiment. The demodulatingcircuit 200 includes the demodulating unit 220 and the decoding unit240.

(Modulating Unit 220)

The demodulating unit 220 according to the present embodiment is acircuit that includes a function to demodulate a multiplexed signalreceived from the receiving circuit 100. Specifically, the demodulatingunit 220 executes processing on a QPSK-modulated signal, for example.The function of the demodulating unit 220 is implemented by a processor,for example.

The demodulating circuit 200 also has a function to estimate SN (SignalNoise) or to estimate CN (Carrier Noise). Here the SN estimation and theCN estimation refer to calculating the ratio of the noise with respectto the signal or carrier by comparing a signal determined by a standardand a signal that is actually received. This calculation of the ratio ofthe noise will be described later.

(Decoding Unit 240)

The decoding unit 240 according to the present embodiment is a decodingcircuit that has a function to decode a multiplexed signal demodulatedby the demodulating unit 220 and extract the core layer data andenhanced layer data. Here the core layer data and enhanced layer datarefer to the data extracted by decoding the core layer signal and theenhanced layer signal respectively. The function of the decoding unit240 is implemented by a processor, for example.

2-3. Configuration Example of Decoding Unit 240 According to Embodiment1

A configuration example of the decoding unit 240 according to anembodiment of the present disclosure will be described next. FIG. 4 is ablock diagram depicting a configuration example of a decoding unit 240according to the present embodiment. The decoding unit 240 includes abuffer unit 10, a core layer decoding unit 20, and an enhanced layerdecoding unit 30.

In the present description, a case where a transmitter, which transmitsa multiplexed signal, executes BCH encoding processing and LDPC encodingprocessing respectively for the two types of signals, performsinterleave, and multiplexes these signals in the LDM system, and areceiver receives this multiplexed signal, will be described.

(Buffer Unit 10)

The buffer unit 10 according to this embodiment has a function to storea multiplexed signal transmitted from the receiving circuit 100. Thebuffer unit 10 also transmits the multiplexed signal to a latermentioned core layer demapping unit 21 or a later mentioned enhancedlayer decoding unit 30.

(Core Layer Decoding Unit 20)

The core layer decoding unit 20 according to the present embodiment is afirst decoding unit that has a function to decode a core layer signalfrom a multiplexed signal. In this case, the core layer decoding unit 20treats the enhanced layer signal as noise. The core layer decoding unit20 includes the core layer demapping unit 21, a core layerdeinterleaving unit 22, a core layer LDPC decoding unit 23 and a corelayer BCH decoding unit 24.

The core layer decoding unit 20 according to the present embodimentreceives, from the demodulating unit 220, noise information to determinewhether decoding processing of the enhanced layer signal is performed.Here the noise information refers to an SN estimation result which is aresult of the SN estimation, or a CN estimation result which is a resultof the CN estimation. The operation of the core layer decoding unit 20using the noise information will be described later.

(Core Layer Demapping Unit 21)

The core layer demapping unit 21 according to the present embodimentexecutes processing to demap the core layer signal, out of themultiplexed signal received from the buffer unit 10 and convert thedemapped core layer signal into a data string of the core layer signal.

(Core Layer Deinterleaving Unit 22)

The core layer deinterleaving unit 22 according to the presentembodiment executes processing to return the data string of the corelayer signal, demapped by the core layer demapping unit 21, back to thestate before interleave was performed.

(Core Layer LDPC Decoding Unit 23)

The core layer LDPC decoding unit 23 according to the present embodimentexecutes processing to LDPC-decode a data string of an LDPC-encoded carelayer signal transmitted from the core layer deinterleaving unit 22. Theresult of the LDPC decoding that is transmitted may include data forparity check.

Further, in the case where the core layer decoding unit 20 determinesthat decoding processing of the enhanced layer signal is performed,based on the noise information related to the reception state of themultiplexed signal received from the demodulating unit 220, the corelayer LDPC decoding unit 23 according to the present embodimenttransmits the result of the LDPC decoding to a later mentioned corelayer interleaving unit 31.

In the case where the core layer decoding unit 23 determines that thereception state of the multiplexed signal is not good, the result of theLDPC decoding is not transmitted to the later mentioned core layerinterleaving unit 31. Here “the reception state is not good” refers tothe multiplexed signal that includes considerable noise, for example.More specifically, “the reception state is not good” refers to theamount of noise that exists in the multiplexed signal is equivalent toor exceeds a predetermined threshold, for example.

(Core Layer BCH Decoding Unit 24)

The core layer BCH decoding unit 24 according to the present embodimentexecutes processing to BCH-decode a BCH-encoded data string transmittedfrom the core layer deinterleaving unit 22. The core layer BCH decodingunit 24 also transmits core layer data, which is a BCH-decoded datastring, to the processing circuit 300.

In the case of the ATSC 3.0 standard, the core layer BCH decoding unit24 may execute processing to perform CRC (Cyclic Redundancy Check)instead of BCH decoding.

Further, in the case where the core layer decoding unit 20 determinesthat decoding processing of the enhanced layer signal is performed basedon the noise information related to the reception state of themultiplexed signal received from the demodulating unit 220, the corelayer BCH decoding unit 24, according to the present embodiment, maytransmit the result of BCH decoding to the later mentioned core layerinterleaving unit 31 instead of the core layer LDPC decoding unit 23.

(Enhanced Layer Decoding Unit 30)

The enhanced layer decoding unit 30 according to the present embodimentis a second decoding unit that has a multiplexed signal received fromthe buffer unit 10, and that a function received from the core layerLDPC decoding unit 23. The enhanced layer decoding unit 30 includes thecore layer interleaving unit 31, a core layer mapping unit 32, an Elayer demapping unit 33, an E layer deinterleaving unit 34, an E layerLDPC decoding unit 35 and the E layer BCH decoding unit 36.

Further, the enhanced layer decoding unit 30 according to the presentembodiment executes processing to acquire the constellation of theenhanced layer signal by subtracting the constellation transmitted bythe later mentioned core layer mapping unit 32 from the constellationtransmitted by the buffer unit 10.

(Core Layer Interleaving Unit 31)

The core layer interleaving unit 31 according to the present embodimentreceives the processing result of the LDPC decoding transmitted from thecore layer LDPC decoding unit 23. The core layer interleaving unit 31also executes the processing to perform interleaving on this result.

(Core Layer Mapping Unit 32)

The core layer mapping unit 32, according to the present embodiment,executes processing to map a data string interleaved by the core layerinterleaving unit 31 on the IQ plane, and acquire the constellation ofthe core layer signal.

(E Layer Demapping Unit 33)

The E layer demapping unit 33 according to the present embodimentexecutes processing to demap the enhanced layer signal reproduced by theenhanced layer decoding unit 30 and convert the result into a datastring.

(E Layer Deinterleaving Unit 34)

The E layer deinterleaving unit 34 according to the present embodimentexecutes processing to return the data string of the core layer signal,demapped by the E layer demapping unit 33, back to the state beforeinterleaving.

(E Layer LDPC Decoding Unit 35)

The E layer LDPC decoding unit 35 according to the present embodimentexecutes processing to LDPC-decode the LDPC-encoded data stringtransmitted from the E layer deinterleaving unit 34.

(E Layer BCH Decoding Unit 36)

The E layer BCH decoding unit 36 according to the present embodimentexecutes processing to BCH-decode the BCH-encoded data stringtransmitted from the E layer deinterleaving unit 34. The E layer BCHdecoding unit 36 also transmits enhanced layer data (E layer data),which is a BCH-decoded data string, to the processing circuit 300.

Operation of the core layer decoding unit 20 using noise informationwill now be described. FIG. 5 is a diagram for explaining SN estimationaccording to the present embodiment. In FIG. 5 , a transmitting point LTand a receiving point LR are indicated on the IQ plane. As mentionedabove, the SN estimation and the CN estimation refer to comparing asignal determined by a standard and a signal actually received andcalculating the ratio of the noise with respect to the signal orcarrier.

The SN estimation according to the present embodiment will now bedescribed. In order to perform the SN estimation, power of the signalduring transmission and power of the noise must be calculated asspecified in the standard. To calculate the power of the signal, a pilotis used. The pilot signal here refers to a signal of a pattern which isdetermined between the transmitting side and the receiving side inadvance. In the case of the ATSC 3.0 standard, three types of pilotsignals exist. These three types of pilot signals have known values.

In FIG. 5 , the distance between the transmitting point LT of the signalduring transmission specified by the standard and the origin indicatesthe power SP of the signal during transmission. The distance between thereceiving point LR of the signal that is actually received and thetransmitting point LT of the signal during transmission specified by thestandard indicates the power NP of the noise. Therefore, the SN ratio isdetermined by dividing the power SP during transmission by the power NPof the noise.

By using the above-mentioned method, the demodulating unit 220calculates the SN ratio based on the received pilot signal. Furthermore,the demodulating unit 220 averages a predetermined number of data of thecalculated SN ratio, calculates the SN estimation result, and transmitsthe SN estimation result to the buffer unit 10. An example of the methodof averaging the data of the SN ratio is a method of determining anaverage value of a number of symbols or an average value in unit time ofthe signals.

Then the core layer decoding unit 20 determines whether the decodingprocessing of the enhanced layer signal is performed or not based on theSN estimation result transmitted from the demodulating unit 220.Specifically, the core layer decoding unit 20 determines whether thedecoding processing of the enhanced layer signal is performed or not inaccordance with the magnitude relationship between the SN estimationresult, which is an averaged SN ratio, and the required SN.

Here the required SN is a threshold to determine whether the decodingprocessing of the enhanced layer signal is performed or not. Therequired SN may be calculated based on the additive white Gaussian noisechannel theory. Based on this theory, the required SN ratio can becalculated using a relational expression of the channel capacity, thebandwidth, and the SN ratio in accordance with this theory.

2-4. Example of Operation Flow of Decoding Unit 240 According toEmbodiment 1

An operation flow of the decoding unit 240 to decode a multiplexedsignal according to the present embodiment will be described next. FIG.6 is a flow chart depicting an example of the operation flow of thedecoding unit 240 to decode a multiplexed signal according to thepresent embodiment.

With reference to FIG. 6 , the buffer unit 10 receives a multiplexedsignal transmitted from the demodulating unit 220 first (S1101). Thenthe core layer decoding unit 20 decodes the multiplexed signaltransmitted from the buffer unit 10 using the core layer demapping unit21, the core layer deinterleaving unit 22, the core layer LDPC decodingunit 23 and the core layer BCH decoding unit 24 (S1102). Then the corelayer decoding unit 20 receives noise information from the demodulatingunit 220 (S1103). Then based on the received noise information, the corelayer decoding unit 20 determines whether the enhanced layer signal isdecoded or not (S1104). In the case where the core layer decoding unit20 determines that the received enhanced layer signal is decoded (S1104:YES), the core layer LDPC decoding unit 23 transmits the result of theLDPC decoding to the core layer interleaving unit 31 (S1105).

Then the enhanced layer decoding unit 30 reproduces the constellation ofthe enhanced layer signal using the core layer interleaving unit 31 andthe core layer mapping unit 32 based on the result of the LDPC decodingtransmitted from the core layer LDPC decoding unit 23 (S1106). Then theenhanced layer decoding unit 30 decodes the enhanced layer signal usingthe E layer demapping unit 33, the E layer deinterleaving unit 34, the Elayer LDPC decoding unit 35, and the E layer BCH decoding unit 36(S1107).

An example of the operation flow of the decoding unit 240 was describedabove.

It should be noted that the core layer decoding unit 20 and the enhancedlayer decoding unit 30 may be a common unit. FIG. 7 is a diagram forexplaining a modification of the decoding unit 240. In FIG. 7 , thedemapping unit 1, the deinterleaving unit 2, the LDPC decoding unit 3,the BCH decoding unit 4, the core layer interleaving unit 31 and thecore layer mapping unit 32 are included.

In FIG. 7 , the demapping unit 1, the deinterleaving unit 2, the LDPCdecoding unit 3 and the BCH decoding unit 4 are used for decoding thecore layer signal and the enhanced layer signal.

As mentioned above, the core layer decoding unit 20 and the enhancedlayer plural number 30 can share hardware in a part of the functionalblocks.

3. EMBODIMENT 2

Embodiment 1 according to the present disclosure was described above.Next Embodiment 2 according to the present disclosure will be described.Essentially redundant content of the description in Embodiment 1 will beomitted, and differences from Embodiment 1 will be described.

3-1. Configuration Example of Decoding Unit 240 According to Embodiment2

FIG. 8 is a block diagram depicting a functional configuration exampleof a decoding unit 240 according to the present embodiment. In FIG. 8 ,the core layer BCH decoding unit 24 transmits the result of the BCHdecoding to the E layer LDPC decoding unit 35, and based on this result,the E layer LDPC decoding unit 35 determines whether the LDPC decodingof the enhanced layer signal is executed or not.

Specifically, the core layer BCH decoding unit 24 transmits theinformation to indicate whether the BCH decoding of the core layersignal succeeded or not to the E layer LDPC decoding unit 35. Based onthis information, the E layer LDPC decoding unit 35 determines whetherthe LDPC decoding of the enhanced layer signal is executed or not,instead of determining whether the enhanced layer signal is decoded ornot based on the noise information described in Embodiment 1.

In the case where information that the BCH decoding of the core layersignal succeeded is received from the core layer BCH decoding unit 24,the E layer LDPC decoding unit 35 executes the LDPC decoding of theenhanced layer signal. In the case where information that the BCHdecoding of the core layer signal failed is received from the core layerBCH decoding unit 24, on the other hand, the E layer LDPC decoding unit35 does not execute the LDPC decoding of the enhanced layer signal.

The core layer BCH decoding unit 24 may transmit the information thatindicates whether the BCH decoding of the core layer signal succeeded ornot to the core layer LDPC decoding unit 23. Then based on thisinformation, the core layer LDPC decoding unit 23 may determine whetherthe result of the LDPC decoding is transmitted to the core layerinterleaving unit 31 or not.

As described above, the signal processing system 1000 according to thepresent embodiment can determine that processing to decode the enhancedlayer signal is performed in the case where the possibility ofsuccessfully decoding of the enhanced layer signal is high, andprocessing to decode the enhanced layer signal is not performed in thecase where this possibility is low. According to this function, themultiplexed signal can be decoded more efficiently.

3-2. Example of Operation Flow of Decoding Unit 240 According toEmbodiment 2

An operation flow of the decoding unit 240 to decode a multiplexedsignal according to Embodiment 2 will be described next. FIG. 9 is aflow chart depicting an example of the operation flow of the decodingunit 240 to decode a multiplexed signal according to Embodiment 2.

With reference to FIG. 9 , the buffer unit 10 receives a multiplexedsignal transmitted from the demodulating unit 220 first (S1201). Thenthe core layer decoding unit 20 decodes the multiplexed signaltransmitted from the buffer unit 10 using the core layer demapping unit21, the core layer deinterleaving unit 22, the core layer LDPC decodingunit 23, and the core layer BCH decoding unit 24 (S1202). Then the corelayer LDPC decoding unit 23 transmits the result of the LDPC decoding tothe core layer interleaving unit 31 (S1203). Then the enhanced layerdecoding unit 30 acquires the constellation of the enhanced layer signalbased on the result of the LDPC decoding transmitted from the core layerLDPC decoding unit 23 using the core layer interleaving unit 31 and thecore layer mapping unit 32 (S1204).

Then the core layer BCH decoding unit 24 determines whether the BCHdecoding of the core layer signal succeeded (S1205). In the case wherethe core layer BCH decoding unit 24 determines that the BCH decoding ofthe core layer signal succeeded (S1205: YES), the core layer BCHdecoding unit 24 transmits the information that indicates this successto the E layer LDPC decoding unit 35 (S1206). The enhanced layerdecoding unit 30 receives this information and decodes the enhancedlayer signal using the E layer demapping unit 33, the E layerdeinterleaving unit 34, the E layer LDPC decoding unit 35, and the Elayer BCH decoding unit 36 (S1206). In the case where the core layer BCHdecoding unit 24 determines that the BCH decoding of the core layersignal failed (S1205: No), on the other hand, the core layer BCHdecoding unit 24 transmits the information that indicates this successto the E layer LDPC decoding unit 35, and based on this information, theE layer LDPC decoding unit 35 does not decode the enhanced layer signal,and operation ends.

4. EMBODIMENT 3

Embodiment 2 according to the present disclosure was described above.Next Embodiment 3 according to the present disclosure will be described.Essentially the redundant content of the description in Embodiment 1 andEmbodiment 2 will be omitted, and differences from Embodiment 1 andEmbodiment 2 will be described.

The decoding unit 240 according to the present embodiment may determinewhether the enhanced layer signal is decoded or not by combining thedetermination based on the SN estimation result according to Embodiment1, and the determination based on the result of the BCH decoding of thecore layer signal performed by the core layer BCH decoding unit 24according to Embodiment 2, for example.

A specific example will now be described. The core layer LDPC decodingunit 23 according to Embodiment 3 transmits the result of the LDPCdecoding to the later mentioned core layer interleaving unit 31 even ifthe SN estimation result is less than the required SN. The E layer LDPCdecoding unit 35 receives the result of this LDPC decoding, anddetermines whether the LDPC decoding of the enhanced layer signal isexecuted or not based on the information that indicates whether the BCHdecoding of the core layer signal transmitted by the core layer BCHdecoding unit 24 succeeded or not.

As described above, according to the signal processing system of thepresent embodiment, the enhanced layer signal can be selectively decodedbased on the noise information and the decoding result of the core layersignal. According to this function, the multiplexed signal can bedecoded more efficiently compared with the case of decoding based on asingle standard.

The operation related to combining the determination based on the SNestimation result and the determination based on the result of the BCHdecoding of the core layer signal performed by the core layer BCHdecoding unit 24 is not limited to the operation described above.Furthermore, the core layer LDPC decoding unit 23 and the E layer LDPCdecoding unit 35 may execute the decoding processing without performingthe above determination.

5. CONCLUSION

As described above, the first signal is decoded from the multiplexedsignal in which the first signal and the second signals are multiplexedby the LDM system, and the second signal is selectively decoded from themultiplexed signal based on the noise information. According to thisfunction, the multiplexed signal can be decoded more efficiently in theLDM system.

While the preferred embodiments of the present disclosure have beendescribed in detail with reference to the accompanying drawings, thetechnical scope of the present disclosure is not limited to theseexamples. It should be understood that various modifications andalterations may be implemented by those skilled in the art within thescope of the technical concept of the appended Claims, and thesemodifications and alterations are included in the technical scope of thedisclosure.

The effects stated in the present description are merely explanatory orexemplary and are not restrictive. In other words, the techniqueaccording to the present disclosure may exhibit other effects that areclear to those skilled in the art based on the description of thepresent description, along with the above-mentioned effects or insteadof the above mentioned effects.

The following configuration is also within a technical scope of thepresent disclosure.

(1)

A decoding circuit including:

-   -   a first decoding unit that decodes a first signal from a        multiplexed signal in which the first signal and a second signal        are multiplexed in an LDM (Layered Division Multiplexing)        system; and    -   a second decoding unit that decodes the second signal from the        multiplexed signal using the decoding result of the decoded        first signal, wherein    -   the second signal is selectively decoded based on noise        information related to a reception state of the multiplexed        signal.

(2)

The decoding circuit according to the above (1), wherein

-   -   the second signal is not decoded in a case where it is        determined that the reception state is not good based on the        noise information.

(3)

The decoding circuit according to the above (1) or (2), wherein

-   -   the second decoding unit decodes the second signal by        subtracting the decoded first signal from the multiplexed        signal.

(4)

The decoding circuit according to any one of the above (1) to (3),wherein

-   -   the first signal is decoded by one or both of first decoding        processing and second decoding processing, and the second signal        is decoded by one or both of the first decoding processing and        the second decoding processing.

(5)

The decoding circuit according to the above (4), wherein

-   -   the first decoding unit sequentially performs the first decoding        processing and the second decoding processing, and the second        signal is decoded using the result of the decoding processing        which is performed first in the first decoding processing and        the second decoding processing.

(6)

The decoding circuit according to the above (4), wherein

-   -   the first decoding unit sequentially performs the first decoding        processing and the second decoding processing, and    -   the second signal is decoded using the result of the first        decoding processing and the second decoding processing.

(7)

The decoding circuit according to any one of the above (4) to (6),wherein

-   -   the first decoding processing is one of LDPC (Low Density Parity        Check) decoding and BCH decoding, and    -   the second decoding processing is the other of the LDPC decoding        and the BCH decoding.

(8)

The decoding circuit according to any one of the above (1) to (7),wherein

-   -   the second signal is selectively decoded further based on the        decoding result of the first signal.

(9)

The decoding circuit according to any one of the above (1) to (8),wherein

-   -   the noise information is acquired by SN (Signal Noise)        estimation or CN (Carrier Noise) estimation.

(10)

The decoding circuit according to any one of the above (1) to (9),wherein

-   -   the first signal and the second signal are signals conforming to        the ATSC (Advanced Television Systems Committee) 3.0 standard.

(11)

The decoding circuit according to any one of the above (1) to (10),wherein

-   -   the first signal is a core layer signal, and    -   the second signal is an enhanced layer signal.

(12)

A decoding circuit including:

-   -   a first decoding unit that decodes a first signal from a        multiplexed signal in which the first signal and a second signal        are multiplexed in an LDM (Layered Division Multiplexing)        system; and    -   a second decoding unit that decodes the second signal from the        multiplexed signal using the decoding result of the decoded        first signal, wherein the second signal is selectively decoded        based on the decoding result of the first signal.

(13)

The decoding circuit according to the above (12), wherein

-   -   the second signal is not decoded in a case where it is        determined that the decoding of the first signal failed.

REFERENCE SIGNS LIST

1000 Signal processing system

100 Receiving circuit

200 Demodulating circuit

220 Demodulating unit

240 Decoding unit

10 Buffer unit

20 Core layer decoding unit

21 Core layer demapping unit

22 Core layer deinterleaving unit

23 Core layer LDPC decoding unit

24 Core layer BCH decoding unit

30 Enhanced layer decoding unit

31 Core layer interleaving unit

32 Core layer mapping unit

33 E layer demapping unit

34 E layer deinterleaving unit

35 E layer LDPC decoding unit

36 E layer BCH decoding unit

300 Processing circuit

The invention claimed is:
 1. A decoding circuit, comprising: circuitryconfigured to: determine noise information related to a reception stateof a multiplexed signal, received via a communication channel, in whicha first signal and a second signal are multiplexed in a layered divisionmultiplexing (LDM) system; decode the first signal from the multiplexedsignal; and selectively decode the second signal from the multiplexedsignal based on a decoding result of the decoded first signal and thedetermined noise information related to the reception state of themultiplexed signal.
 2. The decoding circuit according to claim 1,wherein the noise information includes an amount of noise in themultiplexed signal, the second signal is not decoded based on adetermination that the reception state is not a good reception state,and the reception state is determined not to be the good reception statebased on the amount of noise is more than a threshold value.
 3. Thedecoding circuit according to claim 1, wherein the circuitry is furtherconfigured to decode the second signal based on subtraction of thedecoded first signal from the multiplexed signal.
 4. The decodingcircuit according to claim 1, wherein the first signal is decoded basedon at least one of a first decoding process or a second decodingprocess, and the second signal is decoded based on at least one of thefirst decoding process or the second decoding process.
 5. The decodingcircuit according to claim 4, wherein the circuitry is furtherconfigured to sequentially perform the first decoding process and thesecond decoding process, and the second signal is decoded based on aresult of a decoding processing which is performed first in the firstdecoding process and the second decoding process.
 6. The decodingcircuit according to claim 4, wherein the circuitry is furtherconfigured to sequentially perform the first decoding process and thesecond decoding process, and the second signal is decoded based on aresult of the first decoding process and the second decoding process. 7.The decoding circuit according to claim 4, wherein the first decodingprocess is one of Low Density Parity Check (LDPC) decoding or BCHdecoding, and the second decoding process is the other of the LDPCdecoding or the BCH decoding.
 8. The decoding circuit according to claim1, wherein the noise information is acquired based on one of SignalNoise (SN) estimation or Carrier Noise (CN) estimation.
 9. The decodingcircuit according to claim 1, wherein the first signal and the secondsignal are signals conforming to Advanced Television Systems Committee(ATSC) 3.0 standard.
 10. The decoding circuit according to claim 1,wherein the first signal is a core layer signal, and the second signalis an enhanced layer signal.
 11. A decoding circuit, comprising:circuitry configured to: determine noise information related to areception state of a multiplexed signal, received via a communicationchannel, in which a first signal and a second signal are multiplexed ina layered division multiplexing (LDM) system; decode the first signalfrom the multiplexed signal; and selectively decode the second signalfrom the multiplexed signal based on a decoding result of the decodedfirst signal.
 12. The decoding circuit according to claim 11, whereinthe second signal is not decoded based on a determination that thedecoding of the first signal failed.